Connector means for a light-conductive filament and photosensitive surface

ABSTRACT

A means and method for removably operably connecting a light conducting and directing filament means of small diameter (in the order of 0.005 to 0.020 inches) with a limited or minute lightsensitive area on a photoconductive element such as a phototransistor or photodiode in order to direct and register a maximum amount of radiant energy such as light on the lightsensitive area. The connecting means and method provides precise positioning and holding of an end face of a filament means in spaced relation to the light-sensitive area while permitting removal of the filament means.

u .uleuu LJI'atCD John H. Humphrey Playa Del Rey, Calif. 887,185

Dec. 22, 1969 Dec. 14, 1971 Data Source Corporation El Segundo, Calif.

inventor Appl. No. Filed Patented Assignee CONNECTOR MEANS FOR A LIGHT- CONDUCTIVE FILAMENT AND PHOTOSENSITIVE SURFACE 5 Claims, 7 Drawing Figs.

U.S. Cl 250/227, 350/96 R Int. Cl G02b 5/14 Field of Search 250/227,

[56] References Cited UNiTED STATES PATENTS 3,423,594 l/1969 Galopin 350/96 B X 3,526,880 9/1970 Filippazzi 350/96 B X Primary Examiner- David Schonberg Assistant Examiner-Robert L. Sherman Attorney-Miketta, Glenny, Poms and Smith ABSTRACT: A means and method for removably operably connecting a light conducting and directing filament means of small diameter (in the order of 0.005 to 0.020 inches) with a limited or minute light-sensitive area on a photoconductive element such as a phototransistor or photodiode in order to direct and register a maximum amount of radiant energy such as light on the light-sensitive area. The connecting means and method provides precise positioning and holding of an end face of a filament means in spaced relation to the light-sensitive area while permitting removal ofthe filament means.

0R geese/227 Patented Dec. 14, 1971 2 Sheets-Sheet 1 I/vvEA/ro/e. (IONA/H. Emmy/e59 2 2mm, 5w Jana! 107 TokA/E VJ.

Patented Dec. 14, 1971 3,628,036

2 Sheets-Sheet 2 IN VIE/V708. 26 (IO/0V.- HUMP/665$ CONNECTOR MEANS FOR A LIGHT-CONDUCTIVE FILAMENT AND PHOTOSENSITIVE SURFACE BACKGROUND OF INVENTION Photoconductive elements of transistor or diode type are provided with light-sensitive areas which are quite small. To obtain the most effective response of the photoconductive element to light, it is desirable that maximum amount of light be directed to and registered on the light-sensitive area and that light energy transmitted to the vicinity of the light-sensitive area be not lost by falling upon nonresponsive or low-responsive sections of the photoconductive element. Heretofore, various optical devices were employed for collecting the light and transmitting the light through a collimating means for focusing by means of suitable lenses on the most sensitive portion of the light-sensitive area of the photoconductive ele ment. Under conditions of ample space and ample light energy, such prior proposed arrangements were quite satisfactory. However, in attempts to reduce the size and dimensions of various pieces of equipment to permit selective transmission of small amounts of radiant or light energy directed from variable deflecting or reflecting surfaces, it became difficult to transmit or conduct such light energy to minute light-sensitive areas on photoconductive elements under restricted space conditions which are encountered in the design and construction of solid state" equipment. In such limited space conditions and smallness or minuteness of the light conducting and light sensitive parts involved, it is difficult yet very desirable to precisely removably connect a light-conducting filament with the light-sensitive area of the photoconductive element to provide and assure precise direction of light energy from the end face of the filament and its impingement upon the most effective area of the light-sensitive surface.

A general example of a construction in which the present invention has utility is found in the problem of reading alpha-numeric symbols of various types, such as printed, embossed and debossed characters, and perforated or other data information in the form of code or machine language, and the like. A specific example is the reading of alphabet letters and numerals embossed on a plastic credit card. The size of letters and numerals on an embossed credit card vary somewhat, but generally are in the order of one-eighth inch to three-eighths inch in height. An optical card reader with which the present invention is useful may have a plurality of discrete separate light-conducting filament means, such as a light conducting or transmitting filament made of Lucite or other suitable material, and in which the Iight-receiving ends of such separate filament means are positioned proximate to embossed characters on a credit card in the presence of a light source so that as the card and read head are moved relative to each other, the light reception end faces of the filament means will be subjected to changes in light energy reflected or deflected from the embossed characters during such movement. The light received in each filament means is transmitted to a photoconductive element which is capable of producing an exciting signal in the form of varying current or voltage characteristics. It is desirable that the length of the path of light through the filament means be as short as possible and that the card reader contain the photoconductive elements so that transmission of the signals generated by the photoconductive elements from the card reader may be accomplished by usual electrical conducting means.

In addition to the desirability of compactness of such a card reader, it is also desirable to provide a means whereby each light filament means may be readily removed from the card reader structure and replaced, if necessary. without destruction or disassembly of parts held in fixed assembly.

SUMMARY OF THE INVENTION The present invention, therefore, relates to a means and method for removably connecting or attaching a single filament means to a photoconductive member in a precise relationship to provide maximum effective transmission and direction of radiant energy to a light-sensitive area of a photoconductive member.

An object of the invention is to provide a novel construction wherein one end of a filament means transmitting radiant energy is precisely positioned with respect to a light-sensitive area.

Another object of the present invention is to disclose and provide attachment means precisely positioning one end of a filament means with respect to a light-sensitive surface and including lighbtransmitting portions for maximum registration of the said light on said surface.

A still further object of the present invention is to disclose and provide a method of accurately and precisely affixing a filament holder member to a photoconductive element whereby a filament means may be readily removably connected to the assembly in precise accurate relationship with the light sensitive area of the photoconductor member.

A further object of the present invention is to provide a connector means for a light conducting filament and a light-sensitive area wherein assembly and disassembly of the light-conducting filament is facilitated and readily accomplished without partial destruction or damage to the photoelectric means which carries the light sensitive surface.

Various other objects and advantages of the present invention will be readily apparent from the following description of the drawings in which an exemplary embodiment of the invention is shown.

IN THEDRAWINGS FIG. I is a perspective view of a connector means for a light-conductive filament and a photosensitive surface embodying this invention.

FIG. 2 is a side view of a phototransistor before encapsulation and showing its light-sensitive surface.

FIG. 3 is a schematic perspective view showing alignment of the axis of the connector means with the light-sensitive surface by a microscope means schematically illustrated and swung to one side of the said axis.

FIG. 4 is a fragmentary enlarged sectional view showing the connector means of this invention with a core pin seated on and coaxial with the light-sensitive surface.

FIG. 5 is a fragmentary sectional view showing formation by clear transparent material of a mold about the core pin and the light-sensitive surface.

FIG. 6 is a fragmentary sectional view similar to FIG. 5 illustrating withdrawal of the core pin from the connector device.

FIG. 7 is a sectional view taken in a longitudinal plane passing through the axis of the connector device showing encapsulation of the light-sensitive surface, clear epoxy, and lower end of the connector device, and a light filament or pipe secured in said connector device.

Generally speaking, the means for connecting a light-con ducting means with respect to a light-sensitive area on a photoelectric means is generally indicated at 10 in FIG. 1 and will be referred to as a light pipe connector means. Connector means 10 generally comprises a light-conducting pipe or filament II connected in light-directing relation to a photoelectric means generally indicated at I2 and maintained in operative relation by means, generally indicated at I4, for removably positioning and holding light pipe 11 in operative relation with the photoelectric means 12.

It will be understood that the input end of light pipe 11 receives light reflected or refracted from a light source (not shown) from which light beams are directed to a data or information bearing article including credit cards or other printed, perforated, embossed or debossed characters provided on or in a surface of an article from which information is to be read and transmitted to the output end of light pipe II. The output end of light pipe II directs the transmitted and conducted light onto a light-responsive or light-sensitive surface of the photoelectric means which generates a signal which is amplified. The amplified signal is then transmitted to a reading device for translating into code, machine language, or understandable language the information entering the input end of the light pipe. The connector means 10 is relatively small and is readily adapted to devices having limited space requirements, such as solid state" devices. It will be understood that a plurality of such connector means I may be required to read a particular arrangement of data on a surface and the smallness of the present construction permits a plurality of such connector means to be arranged in a straight line or in rows in a matrixlike device without occupying substantial space.

The photoelectric means generally indicated at 12 is best seen in FIG. 2 and may comprise a suitable photoconductor means, such as a phototransistor, photodiode or the like in which a light-sensitive area or surface is provided on a chip 21 carried on a collector element 22 of an exemplary phototransistor 23. The phototransistor 23 in this example may comprise a disclike body 26 initially having a base lead 27, a collector lead 28 and an emitter lead 29. The collector lead 28 may carry the chip 21 on a flattened thin plate 30. Usually, transistors of this type are obtained from the manufacturer in encapsulated condition, that is the disc body 26, the plate 30 and the leads 27, 28 and 29 in the vicinity of the disc body 26 are completely enclosed and covered by dielectric epoxylike material which may be transparent or opaque. In the practice of the present method, it is desirable to obtain the phototransistor bodies before encapsulation.

In usual manufacture of a phototransistor, the base lead 27 is connected by a wire (not shown) to the collector lead 28 and chip 21. This wire is removed and the base lead 27 is made inoperable. The wire 32 between the chip 21 and the emitter lead is not removed so that a connection is maintained between the leads 28 and 29. The light-sensitive area 20 is schematically illustrated and the shape of area 20 may vary depending upon the type and manufacture of phototransistor or photodiode used. It will be understood that light conducted by light pipe 11 should be directed against substantially the entire area of the light-sensitive surface 20 in order that all available light or radiant energy can be transmitted to the light-sensitive surface and thus enhance the strength of the signal being generated by the surface 20. Since the light-sensitive area is very small, that is in the nature of 1.8 square millimeters, and the diameter of the light pipe may be in the order of 0.005 to 0.010 inches, the axis of the light pipe must be precisely located and held with respect to the center 20a of area of the light-sensitive surface. The present invention will be best understood by describing the method of making the connector means I0 as set forth below.

In order to precisely align light pipe 11 with the center of area 20, a suitable microscope 33 on a support or fixture is employed, the microscope having an optical axis 33a. A test light filament (not shown) of the same diameter to be used is connected with a test light source and the phototransistor is connected with a suitable instrument to read the response of the lightsensitive surface 20. The output end of the test filament is aligned with the optical axis of the microscope. The transistor, mounted on a clamp 42 associated with the microscope, is then moved relative to the test filament output end until it is positioned for maximum light response as indicated by the test instrument, and is then clamped in place. When this position of the microscope is obtained, the microscope can be swung to one side about its mounting axis and a holder member 34 having a through bore 35 may be precisely located by the microscope fixture, by means of microscope fixture stops, with the axis of the through bore in alignment with the effective center of the light-sensitive surface as determined by the test filament.

The phototransistor 23 is held in fixed immovable relation by securing the disc body 26 in a suitable clamp 42 associated with the microscope fixture in well-known manner.

An elongated cylindrical core pin 36 having a diameter permitting a sliding fit with through bore 35 at its lower end at 37 may then be inserted in through bore 35 until its end face 38 seats or lightly rests on the light-sensitive surface. End face 38 is provided on a cylindrical reduced end tip 39 of core pin 36, the reduced tip 39 having a diameter corresponding approximately to or less than the diameter of the light-conducting filament 57. Tip 39 also provides an annular shoulder 40 spaced a selected distance from end face 38 which may be in the order of0.00l to 0.006 inches.

When core pin 36 is thus precisely located on the light sensitive area and its axis is centered on the effective center of the light-sensitive area, a light-transmitting material 44, such as a suitable dielectric plastic material such as a thermosetting clear epoxy, may be applied in a semifluid state and deposited on the transistor disclike body 26, end portion 45 of the holder member 34, the chip 2], and at least portions of the collector and emitter leads 28 and 29. As shown in FIG. 5, the clear material 44 completely surrounds the end of core pin 36 and the chip 21 and forms with the reduced end 39 of core pin 36 a reduced open through bore 46 (FIG. 6) coaxial with the center of the light-sensitive surface, and an annular shoulder 47.

Core pin 36 may then be withdrawn from holder member 34 as indicated in FIG. 6 or it may be maintained within the holder member in seated relation on the light sensitive surface during the next step of the process of the invention.

Since the clear epoxy 44 surrounds the light-sensitive surface, it will be apparent that stray light may energize the lightsensitive area 20. Therefore, in order to prevent unwanted light from impinging upon the light-sensitive area and to securely hold and maintain the phototransistor and holder member in permanent assembly, an opaque semifluid or pasty epoxy material is deposited over the clear material 44 and the end portion 37 of the holder member as well as the entire transistor disc body 26 and the collector, emitter and base leads adjacent the body 26. The thermosetting opaque epoxylike material completely surrounds, encloses and encapsulates the structure described aforesaid and thus forms a solid fixed connection between the holder member 34 and the phototransistor 23. Moreover, the axis of the holder member 34 is permanently fixed in coincident or coaxial relation with bore 46 and the center of the light-sensitive area. If the core pin had been retained in the holder member during the second epoxy deposition operation, it is now removed from the holder member.

The holder member 34 may be of any suitable cross-sectional configuration and includes an externally threaded end portion 50 opposite to end portion 37 and an annular end face 51 of reduced diameter. A cap member 52 of cuplike configuration provided with internal threads engages as at 53 external threads on end portion 50. Between end wall 54 of cap 52 and end face 51 of end portion 50 may be seated an annular torus or O-ring 55 of resilient flowable material such as rubber, or suitable rubberlike composition materials, and having an inner diameter or opening sufficient to permit passage of light pipe I 1.

Light pipe 11 is preferably made with a light-transmitting or light-conducting filament 57 of suitable flexible pliant material, such as narrow threadlike filament of Lucite, and capable of efficiently transmitting and conducting radiant energy or light along its length without loss of light through its cylindrical surface which may be suitably coated to serve as an optical fiber. To protect and preserve light filament 57, an outer protection tube 58 of flexible plastic material may loosely receive light filament 57 to facilitate its insertion and removal from tube 58. The outer diameter of tube 58 is essentially the same as that of core pin 36 so that it may be readily received within the internally formed enlarged portion 46a of bore 46 with its end seated on shoulder 47.

Thus when light pipe means 11 is inserted through axial bore 60 in wall 54 of cap 52 and its output end face is seated as at 61 on the formed shoulder 47, the axis of the light pipe will be coaxial with the axis of the through bore and the effective center of the light-sensitive surface. Upon seating of the output end of the light pipe means 11 on shoulder 47, the cap 52 may be threadedly tightened to axially compress resilient ring 55 to cause its inner circumferential portions to flow radially inwardly to tightly engage and frictionally grasp the adjacent surface of the light pipe means 11 to firmly hold the tube 58 and light filament 57 therein in the most effective optimum position with respect to the light-sensitive surface.

When the connector means has been assembled as described above, it will be apparent that light conducted along the light filament 57 will exit from the end face of the light filament and be directed upon the light sensitive surface through the open reduced bore 46 in the clear material 44. Since annular edge margins of the exit face of light filament 57 may partially seat upon the shoulder 47, light conducted through outer cylindrical portions of the light pipe will be directed to the light-sensitive area through portions of the clear epoxy material 44 surrounding the open bore 46. Thus, substantially all of the light conducted by the filament will be directed against and impinge upon the light-sensitive area of the phototransistor to thereby generate or excite a signal which will be conducted through the collector and emitter leads to a suitable amplifier (not shown). The amplifier is connected through various means to a data memory unit or other suitable device for reading or interrupting the response of the lightsensitive area to the conducted light. A device for this purpose is shown and described in my copending application Ser. No. 848,769 filed Aug. 5, 1969 which discloses a credit card reader utilizing light pipes or filaments of the type described above.

if desired, the space between the exit face of light filament 57 and light-sensitive surface may be varied and in some constructions it may be desirable to lightly seat the face on the light-sensitive area. However some space between surface 20 and filament 57 has appeared to be desirable in order to most effectively match the differently shaped areas of surface 20 and the exit face of the filament to obtain the least light loss and to utilize the maximum effective area of surface 20.

it is important to note that in the event a light filament becomes damaged in the portion outside of the connector means or if it may be desirable to replace or repair a light filament, such replacement can be readily accomplished by simply unthreading cap 52 to release the frictional engagement of resilient ring 55 with the tube 58 and then pulling outwardly the end of the light pipe means 11 held in the holder member. A new or replacement light filament 57 or pipe means 11 may be readily inserted and selectively affixed and connected to the holder member in precise selected position with respect to light-sensitive area 20. Thus, repair or replacement of this portion of the light transmitting and conducting means is conveniently and quickly accomplished.

Preferably light filament 57 comprises a single light filament or thread for conducting radiant energy or the like from the input end of the filament to the output end. In some instances, it may be desirable to use a bundle of very thin filaments and in such event such a bundle of very thin narrow light-conducting filament may be readily employed in the connector means described above, it being understood that the outer diameter of the bundle of light filaments does not exceed the inner diameter of the protective tube 58.

it will be understood that in the above-described example,

base lead 27 of the transistor has been disconnected and made inoperative. It may be desirable in some installations to modify the sensitivity of surface 20 with respect to adjacent phototransistors and such modification may be readily accomplished by imposing a biasing voltage on the transistor through the base lead 27.

The connector means 10 described above effectively transmits and directs radiant or light energy unto a light sensitive and responsive surface or area in a precise accurate manner so that a maximum amount of energy available falls on the maximum available light-sensitive area. The connector means is readily secured and the light pipe means 11 is readily removed and is replaceable in precise position.

Vanous modifications and changes may be made in the construction described above which come within the spirit of the present invention.

lclaim:

1. Means for connecting a light-conducting means with respect to a light-sensitive area on a photoelectric means to precisely direct conducted light thereon, comprising in combination:

a photoelectric means including a light-sensitive surface lying in a plane;

means for directing and conducting light from a remote source onto such surface;

said light-conducting means including a single filament means having an exit face lying in a plane spaced from and parallel to said light-sensitive surface and defining a space therebetween;

means for positioning and holding said filament means with its exit face in light transfer relationship to said light sensitive surface;

clear light-transmitting material means surrounding and shielding said exit face and said light-sensitive surface at said space;

and means for removing said filament means and its exit face from said spaced light transfer relationship with respect to said light-sensitive surface.

2. In a means as stated in claim I wherein said positioning and holding means includes a seat for one end of said filament means formed in said clear light-transmitting material means.

3. In a means as stated in claim 1 wherein said positioning and holding means includes a holder member having a throughbore to receive said single filament means;

and attachment means adjacent said exit face for securing said holder member to said photoelectric means.

4. In a means as stated in claim 3 wherein said attachment means includes an outer mass of opaque material surrounding such light sensitive surface, said light-transmitting material means, and at least a portion of said holder member.

5. In a means as stated in claim 3 wherein said releasable, frictional securement means includes a cap member having an opening aligned with said throughbore;

and means between said cap member and said holder member for frictionally holding said filament means.

I! I II i 

1. Means for connecting a light-conducting means with respect to a light-sensitive area on a photoelectric means to precisely direct conducted light thereon, comprising in combination: a photoelectric means including a light-sensitive surface lying in a plane; means for directing and conducting light from a remote source onto such surface; said light-conducting means including a single filament means having an exit face lying in a plane spaced from and parallel to said light-sensitive surface and defining a space therebetween; means for positioning and holding said filament means with its exit face in light transfer relationship to said light sensitive surface; clear light-transmitting material means surrounding and shielding said exit face and said light-sensitive surface at said space; and means for removing said filament means and its exit face from said spaced light transfer relationship with respect to said light-sensitive surface.
 2. In a means as stated in claim 1 wherein said positioning and holding means includes a seat for one end of said filament means formed in said clear light-transmitting material means.
 3. In a means as stated in claim 1 wherein said positioning and holding means includes a holder member having a throughbore to receive said single filament means; and attachment means adjacent said exit face for securing said holder member to said photoelectric means.
 4. In a means as stated in claim 3 wherein said attachment means includes an outer mass of opaque material surrounding such light sensitive surface, said light-transmitting material means, and at least a portion of said holder member.
 5. In a means as stated in claim 3 wherein said releasable, frictional securement means includes a cap member having an opening aligned with said throughbore; And means between said cap member and said holder member for frictionally holding said filament means. 